Streaks come from the water you used, the cloth you dried with, or the time of day you did it.
Advice · EKL Cleaning
Almost every streak we get called out to fix comes down to one of three causes: the water, the cloth, or the sun. Get those right and the glass comes clear. Get them wrong and you can scrub a window for twenty minutes and leave it looking worse than when you started.
When we are called in to clean up after another company, streaky windows are the single most common thing we find. Usually the person worked plenty hard and the method fought them the whole way.
Tap water around Metro Vancouver carries dissolved minerals. When a pane dries, the water evaporates and those minerals stay behind on the glass as a fine film. That film is what you are looking at when a window dries cloudy an hour after you finished it.
This is why we run a water fed pole with a 100% pure filtered water system on the higher outside windows. The filtering takes the minerals out first, so when the water dries there is nothing left on the glass to leave a mark. Every pane gets scrubbed and then rinsed with that pure water, and it dries clear on its own with nothing touching it.
At home, the closest you will get is distilled water rather than straight from the tap. It will not match a filtered system, but it beats hard tap water by a wide margin.
Sun on the glass dries your cleaning solution before you have finished spreading it. The solution sets in patches, and every patch edge becomes a line. Work on an overcast day, or follow the shade around the house and do each side while it is out of the sun. In Vancouver this is the easiest rule to follow all year.
Paper towel sheds lint onto the glass and pushes dirt around instead of lifting it. A proper squeegee with a sharp rubber blade pulls the water off in one pass, which is the whole point. Wipe the blade with a clean cloth after every stroke, or you just redeposit what you removed.
We do detail work with a mop and squeegee by hand, one pane at a time, and we wet only as much glass as we can pull before it starts to dry. Trying to do a whole wall of windows at once is how people end up chasing dried edges.
Dirt sitting in the frame and the sill washes back down onto clean glass the first time it rains. Anyone who cleans the pane and leaves the frame is buying themselves a week. We scrub the frames, sills and panes together for exactly this reason.
Customers ask us this one constantly, usually about a window that has been sitting with mineral deposits and grime on it for years. It is the moment that sticks with us most on a job: people do not expect a real difference, and then they see one.
Built-up mineral staining does not come off with a household spray. It needs the right product and the right tools, applied so the glass is not scratched in the process. This is the point where doing it yourself stops being worth the weekend, and it is a large share of the calls we get.
Use water without minerals in it, work out of direct sun, pull the water off with a squeegee and dry the blade between strokes, and clean the frame and the sill along with the glass. That is most of the job. The rest is patience and doing one pane at a time.
